/*
 * Copyright 2012-2019 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.boot.context.properties;

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * 表示 {@link ConfigurationProperties @ConfigurationProperties} 对象中的字段
 * 应被视为嵌套类型。此注解不会影响实际的绑定过程，
 * 但被 {@code spring-boot-configuration-processor} 用作提示，表示该字段不是绑定为单一值。
 * 指定此注解时，会为该字段创建嵌套组并提取其类型。
 * <p>
 * 该注解对集合和映射无效，因为这些类型会被自动识别。
 *
 * @author Stephane Nicoll
 * @author Phillip Webb
 * @since 1.2.0
 */
@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface NestedConfigurationProperty {

}
